Leetcode 554 砖墙 虚拟单位与前缀和

　　虚拟单位解法 JAVA：

    /**
     * @Author Niuxy
     * @Date 2020/11/16 11:29 下午
     * @Description 虚拟砖块
     */
    public final int leastBricks(List<List<Integer>> wall) {
        int[] column = new int[wall.size()];
        int sum = 0, res = Integer.MAX_VALUE;
        for (int i = 0; i < wall.get(0).size(); i++) sum += wall.get(0).get(i);
        for (int i = 0; i < sum; i++) {
            int currentColumnRe = 0;
            for (int j = 0; j < wall.size(); j++) {
                List<Integer> row = wall.get(j);
                if (row.get(column[j]) == 0) column[j]++;
                else currentColumnRe++;
                row.set(column[j], row.get(column[j]) - 1);
            }
            res = Math.min(res, currentColumnRe);
        }
        return res;
    }

　　前缀和解法 JAVA：

    public final int leastBricks(List<List<Integer>> wall) {
        Map<Integer, Integer> map = new HashMap<Integer, Integer>();
        for (List<Integer> row : wall) {
            int gap = 0;
            for (int i = 0; i < row.size() - 1; i++) {
                gap += row.get(i);
                if (map.containsKey(gap)) map.put(gap, map.get(gap) + 1);
                else map.put(gap, 1);
            }
        }
        Iterator<Integer> iterator = map.keySet().iterator();
        int maxGap = 0;
        while (iterator.hasNext()) {
            int key = iterator.next();
            maxGap = Math.max(maxGap, map.get(key));
        }
        return wall.size() - maxGap;
    }

　　前缀和解法 JS：

/**
 * @param {number[][]} wall
 * @return {number}
 */
var leastBricks = function (wall) {
    let map = new Map();
    for (let i = 0; i < wall.length; i++) {
        let gap = 0;
        for (let j = 0; j < wall[i].length - 1; j++) {
            gap += wall[i][j];
            if (!map.get(gap)) map.set(gap, 1);
            else map.set(gap, map.get(gap) + 1);
        }
    }
    let maxGap = 0;
    map.forEach((key) => {
        maxGap = Math.max(maxGap, key);
    })
    return wall.length - maxGap;
};